<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../react18/react.development.js"></script>
    <script src="../react18/react-dom.development.js"></script>
    <script src="../react18/babel.min.js"></script>
</head>

<body>
    <div id="app"></div>
    <script type="text/babel">
        class App extends React.Component {
            constructor(){
                super();
                //构造器中的this指向组件实例
                this.handle=this.handle.bind(this)
            }
            state = {
                count: 0
            }
            render() {
                const { count } = this.state;
                return (
                    <div>
                        <button onClick={this.handle}>+</button>
                        <p>{count}</p>
                    </div>
                )
            }
            handle() {
                let {count} = this.state;
                this.setState({count:count+1})
        }
        }
        
        const root = ReactDOM.createRoot(document.getElementById('app'));
        root.render(<App/>)

    </script>

</body>

</html>